Despite the predominance of arguments in the prior art for designing video compression systems that eliminate drift, the present invention is based on the observation that if one can effectively manage error propagation in both a one-layer encoder and a two-layer encoder that does not allow the introduction of base-layer drift, it is possible to design an encoder that does allow the introduction of drift into the base-layer.
It is an object of the invention to provide means to introduce drift incrementally.
It is an object of the invention to provide a way for the encoder to measure the drift being potentially introduced.
It is an object of the invention to provide encoding options that can allow drift, while simultaneously keeping the amount of drift under control.
It is an object of the invention to provide means to drastically reduce or eliminate drift without the need for a full I-frame.
It is an object of the invention to provide a system-level optimization, designed to maximize expected quality across all expected receivers.
The present invention is directed to structures for scalability that use previous enhancement-layer information in a video stream to predict the current base-layer, while simultaneously managing the resulting possibility of drift. These structures allow better compression efficiency, while introducing only limited impairments in the quality of the reconstruction.
These and other advantages of the invention will be apparent to those of ordinary skill in the art by reference to the following detailed description and the accompanying drawings.